The goal of the proposed research is to examine the cost effectiveness of complementary and alternative medicine (CAM) in reducing musculoskeletal (MSD)-related pain and MSD-pain comorbidities among Veterans of OEF/OIF/OND wars. The specific aims are to: (1) to determine the extent of CAM use; (2) determine the cost of that CAM use; (3) determine the cost effectiveness of adjunctive CAM use compared to usual care alone as well as the healthcare cost impact of CAM use with both pain and pain-comorbid conditions; and (4) obtain feedback on CAM use, CAM costs and study results to better facilitate the integration of those results into recommendations for VA delivery f CAM, using an advisory board of key VA stakeholders. Methods: This study will capitalize on the existing VA MSD Cohort dataset, a comprehensive set of data on health care use and costs and patient and facility characteristics, and on the recent uploading of individual CAM notes to the VA's centralized data analysis platform (VINCI). We will use natural language processing (NLP) data mining methods to extract CAM use data from narrative medical record notes, focusing on the top ten CAM modalities used for MSD pain according to the VA's Healthcare Analysis & Information Group (HAIG) report. We will the VA MSD pain population using the set of pre-designated ICD-9 codes used in the VA MSD Cohort data. We will compare those who used CAM to matched controls who did not use CAM for their MSD pain using doubly robust estimation methods. We also will examine the impact of the amount of ten different types of CAM. Additionally, we will examine the impact of CAM use on pain comorbidities such as traumatic brain injury (TBI) and mental health conditions (PTSD, substance abuse disorder, sleep disturbance, anxiety, and depression). To address any large variation in results and to enable confidence in the answers generated, we will perform sensitivity analyses. The advisory board will contain the VA's national leaders in pain treatment and policy and CAM policy and delivery. Significance: Chronic MSD pain and its co- morbidities are costly to treat and highly prevalent among OEF/OIF/OND Veterans. CAM appears to be in widespread use for pain management at the VA. However, little is known about what types of CAM are used, the costs of providing CAM, and whether this CAM use results in reductions in healthcare costs (including opioid use) among those with MSD pain and those with MSD pain and its mental health comorbidities and TBI. The results of this cost-effectiveness study will help the VA determine if CAM, and what particular types of CAM, is an efficient way to reduce MSD pain and its co-morbid conditions given limited resources. The results will also be useful to other large healthcare organizations in terms of providing information on the costs and impacts of one model of how CAM services could be delivered. Innovation: This will be the first widespread study of the overall impact of CAM use on healthcare utilization and health care cost at the VA. This also will be the first multi-site examination of individual-level CAM use among Veterans with MSD pain.